Computer aided three-dimensional analysis of nostril forms: application innormal and operated cleft lip patients

The appearance of the nostril in cleft lip patients is very important in th e subjective assessment of naso-labial forms and patient satisfaction. To i mprove the outcome of plastic surgery, a computer aided diagnostic system w as developed. Facial forms were measured with a three-dimensional optical s canner (Ogis Range Finder RFX-IV) XYZ coordinates (256x240) and RGB (red, g reen, blue) image (512x480) data sets were then obtained with the apparatus . The nostril area was determined by discriminant analysis of the RGB data, and the landmarks of the nostril were extracted under geometric conditions . To assess the reliability of this technique with head inclination, five v olunteers were measured in seven postures. Landmark stability was within ap proximately 1 mm when the Frankfort plane was 45-60 degrees. Subsequently, this system was applied to two cleft lip patients who had undergone a secon dary nasal correction. For control data, 37 healthy adults (22 males and 15 females) were measured in the same manner. Nasal asymmetry in the unilater al case and wide and flat nostrils in the bilateral case were greatly impro ved after surgery. Conversely, the volume of the nasal tip decreased. This system was a great help in the diagnosis of nostril abnormalities. (C) 1999 European Association for Cranio-Maxillofacial Surgery.